The commitment in the Paris Agreement to keep average global warming “well below” 2°C has cut the remaining “atmospheric space” for carbon reductions in half, from 2,390 to 1,240 billion tons from 2015 onward, according to a paper in the journal Nature Climate Change.
“In order to have a reasonable chance of keeping global warming below 2°C, we can only emit a certain amount of carbon dioxide, ever. That’s our carbon budget,” said Joeri Rogelj, research scholar at Austria’s International Institute for Applied Systems Analysis. “This study shows that, in some cases, we have been overestimating the budget by 50 to more than 200%. At the high end, this is a difference of more than 1,000 billion tons of carbon dioxide.”
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The study team looked at the wide variances in past carbon budget calculations, attributing them to the complexity of the calculations and the differences in the assumptions and methodologies involved.
“We now better understand the carbon budget for keeping global warming below 2°C,” Rogelj said. “We have figured out that this budget is at the low end of what studies indicated before, and if we don’t start reducing our emissions immediately, we will blow it in a few decades.” (h/t to Resilience.org for first pointing us to this story)